1. Field of the Invention
This invention relates to a disc drive having a tray, and more particularly to a load/unload control system and a method for loading/unloading the tray.
2. Description of Related Art
Optical disc drives, such as video compact disc (VCD) players, digital versatile disc (DVD) players, or computer data disc reading/writing drives are widely used for recording information onto and/or reproducing information from discs.
Most optical disc drives use trays to load and unload the discs. As shown in FIG. 7, a portion of a traditional optical disc drive 10 is illustrated. The optical disc drive 10 includes a tray 12, a gear train 14, and a motor 16. The motor 16 connects to the gear train 14 with a belt 18. A driven gear of the gear train 14 meshes with a gear rack 122 formed on the tray 12.
The motor 16 drives the gear train 14 to rotate so as to bring the tray 12 to move between a close position and an open position. When the tray 12 ejects out of the optical disc drive 10 to the open position, an optical disc (not shown) can be placed on/removed from the tray 12. When the tray 12 moves into the optical disc drive 10 to the close position, the optical disc drive 10 can reproduce/record information from/on the optical disc.
A moving speed of the tray 12 is determined by a rotational speed of the motor 16, and the rotational speed of the motor 16 is controlled by a voltage supplied to the motor 16. In other words, the voltage applied to the motor 16 determines the moving speed of the tray 12.
Referring also to FIG. 8, a constant voltage is applied to drive the motor 16. In order to shorten a(n) load/unloading time, the constant voltage is usually set to a relatively high voltage value. When the optical disc drive 10 starts loading the tray 12 from the open position, the voltage increases from zero to a relatively high voltage value instantaneously. The motor 16 accelerates to a high rotational speed in a very short time, driving the tray 12 to reach the moving speed from rest at a relatively high acceleration. This may produce unwanted vibrations on the tray 12 because the tray 12 extended out of the disc drive 10, an extended portion of the tray 12 is not supported by the disc drive 10. Similarly, during the end of an unload process, the constant voltage is terminated instantaneously when the tray 12 reaches the open position, the extended portion of the tray 12 lacks support and vibrations may also occur as the tray 12 stops suddenly from a high speed.
Therefore, a load/unload control method which is capable of reducing the unwanted vibrations is desired.